1. Field of the Invention
The disclosures herein generally relate to a projection lens unit, an optical engine, and an image projecting apparatus.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2013-64866 discloses an image projecting apparatus. The image projecting apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2013-64866 includes an image generating unit that uses light emitted from a light source to generate and emit image light, and a projection optical system unit that projects the image light emitted from the image generating unit on a projection plane.
The projection optical system unit includes a projection lens unit. The projection lens unit includes a plurality of projection lenses that transmit and emit the image light from the image generating unit, and a barrel that holds the plurality of projection lenses.
However, in the projection lens unit disclosed in Japanese Unexamined Patent Application Publication No. 2013-64866, the barrel becomes hot due to heat of the image light if the image light falls on the barrel when transmitting the plurality of projection lenses. Thus, a positional deviation of the projection lenses may occur due to thermal expansion of the barrel. As a result, quality of the image light such as color definition may be degraded.